U.S. patent number 10,165,167 [Application Number 15/934,159] was granted by the patent office on 2018-12-25 for non-canting vcm-actuated autofocus.
This patent grant is currently assigned to Google LLC. The grantee listed for this patent is Google LLC. Invention is credited to Guangxun Liao, Philip Sean Stetson.
United States Patent |
10,165,167 |
Stetson , et al. |
December 25, 2018 |
Non-canting VCM-actuated autofocus
Abstract
Techniques and apparatuses are described that enable non-canting
VCM-actuated autofocus. These techniques and apparatuses enable
multiple focal distances that are substantially free of imaging
errors caused by canting of a lens housing. These multiple focal
distances are provided by multiple positions of a lens housing
relative to an image sensor. These positions can be free of cant
through use of mechanical stops and corresponding mechanical
stop-mates. By so doing, lower cost, faster focusing, higher image
quality, lower power, or lower settling time can be achieved.
Inventors: |
Stetson; Philip Sean (Wexford,
PA), Liao; Guangxun (San Jose, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Google LLC |
Mountain View |
CA |
US |
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Assignee: |
Google LLC (Mountain View,
CA)
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Family
ID: |
57588669 |
Appl.
No.: |
15/934,159 |
Filed: |
March 23, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20180213133 A1 |
Jul 26, 2018 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15175318 |
Jun 7, 2016 |
9961246 |
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62181516 |
Jun 18, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N
5/2254 (20130101); H04N 5/2257 (20130101); H04N
5/23212 (20130101); H04N 5/247 (20130101); H04N
5/2258 (20130101); H04N 5/332 (20130101) |
Current International
Class: |
H04N
5/225 (20060101); H04N 5/232 (20060101); H04N
5/33 (20060101); H04N 5/247 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
"First Action Interview OA", U.S. Appl. No. 15/175,318, dated Oct.
23, 2017, 5 pages. cited by applicant .
"Notice of Allowance", U.S. Appl. No. 15/175,318, dated Dec. 29,
2017, 9 pages. cited by applicant .
"Pre-Interview Office Action", U.S. Appl. No. 15/175,318, dated
Sep. 29, 2017, 4 pages. cited by applicant.
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Primary Examiner: Jerabek; Kelly L
Attorney, Agent or Firm: Colby Nipper
Parent Case Text
RELATED APPLICATIONS
This application claims priority under 35 U.S.C. .sctn. 119(e) to
U.S. patent application Ser. No. 15/175,318 filed on Jun. 7, 2016
which claims benefit of Provisional Application Ser. No. 62/181,516
filed Jun. 18, 2015, the disclosure of which is incorporated by
reference herein in its entirety.
Claims
What is claimed is:
1. A camera system comprising: an image sensor; and a lens housing
having: a lens-retention section configured to retain one or more
lenses capable of focusing light from a scene onto the image
sensor; and a mechanical stop configured to contact a mechanical
stop-mate, the mechanical stop-mate including three or more
projections, the three or more projections arranged effective to
define a stop plane, the stop plane parallel to a planar cross
section of at least one of the lenses, the planar cross section
parallel to a plane of the image sensor, the mechanical stop
configured to contact the mechanical stop-mate at the three or more
projections effective to prevent cant of the lens housing.
2. The camera system as recited in claim 1, further comprising a
second mechanical stop, the first-mentioned mechanical stop and the
second mechanical stop both effective to prevent cant of the lens
housing, the first-mentioned mechanical stop at a first position
and the second mechanical stop at a second position, the first and
second positions having different focal distances to the image
sensor.
3. The camera system as recited in claim 1, wherein the mechanical
stop-mate comprises a ring surrounding the lens housing, the ring
configured to contact the mechanical stop with the three or more
projections when in a first position and further configured to
contact a second mechanical stop with three or more other
projections when in a second position, the first and second
positions having different focal distance to the image sensor.
4. The camera system as recited in claim 1, wherein the mechanical
stop and the mechanical stop-mate are configured to mate sufficient
to prevent the cant and to further prevent non-cant movement of an
image center of the scene on the image sensor.
5. The camera system as recited in claim 4, wherein the mechanical
stop includes three or more concave structures corresponding to the
three or more projections of the mechanical stop-mate, the
projections and the concave structures permitting axial
perpendicular movement relative to the plane of the image sensor
while prohibiting, on full contact, axial parallel movement
relative to the plane of the image sensor.
6. The camera system as recited in claim 5, wherein the projections
and concave structures are matching conic, pyramid, or
narrow-to-wide structures.
7. The camera system as recited in claim 1, further comprising a
second image sensor, a second lens housing having a second
lens-retention section configured to retain one or more other
lenses capable of focusing light from the scene onto the second
image sensor and a second mechanical stop-mate configured to
contact a second mechanical stop, the second mechanical stop
configured to contact the second mechanical stop-mate effective to
prevent cant of the second lens housing relative to a second planar
cross section of at least one of the second lenses, the second
planar cross section parallel to a second plane of the second image
sensor.
8. The camera system as recited in claim 7, further comprising an
image manager configured to receive first and second images from
the first and second image sensors, respectively, and combine or
process the first and second image sensors to create a composite
image of the scene.
9. An array camera system comprising: a first image sensor; a first
lens housing having a first lens-retention section configured to
retain one or more first lenses capable of focusing light from a
scene onto the first image sensor and a first mechanical stop-mate
configured to contact a first mechanical stop; the first mechanical
stop, the first mechanical stop configured to contact the first
mechanical stop-mate effective to prevent cant of the first lens
housing relative to a first planar cross section of at least one of
the first lenses, the first planar cross section parallel to a
plane of the first image sensor; a second image sensor; a second
lens housing having a second lens-retention section configured to
retain one or more second lenses capable of focusing light from the
scene onto the second image sensor and a second mechanical
stop-mate configured to contact a second mechanical stop; and the
second mechanical stop, the second mechanical stop configured to
contact the second mechanical stop-mate effective to prevent cant
of the second lens housing relative to a second planar cross
section of at least one of the second lenses, the second planar
cross section parallel to a plane of the second image sensor.
10. The array camera system as recited in claim 9, wherein the
first or second mechanical stop includes three or more projections,
the three or more projections arranged effective to define a stop
plane, the stop plane parallel to the first or second planar cross
section and the plane of the first or second image sensor,
respectively.
11. The array camera system as recited in claim 9, wherein the
first or second mechanical stop includes a flat structure defining
a stop plane, the stop plane parallel to the first or second planar
cross section and the first or second plane of the first or second
image sensor, respectively.
12. The array camera system as recited in claim 9, wherein the
first or second mechanical stop-mate comprises a ring surrounding
the first or second lens housing, the ring configured to contact
the first or second mechanical stop when in a first position and a
third mechanical stop with in a second position, the first and
second positions having different focal distance to the first or
second image sensor, respectively.
13. The array camera system as recited in claim 9, wherein the
first or second mechanical stop and the first or second mechanical
stop-mate are configured to mate sufficient to prevent the cant and
to further prevent non-cant movement of an image center of the
scene on the first or second image sensor, respectively.
14. The array camera system as recited in claim 13, wherein the
first or second mechanical stop includes a convex or concave
structure and the first or second mechanical stop-mate includes the
other of the convex or concave structure, the convex and the
concave structures permitting axial perpendicular movement relative
to the plane of the first or second image sensor while prohibiting,
on full contact, axial parallel movement relative to the plane of
the first or second image sensor, respectively.
15. The array camera system as recited in claim 14, wherein the
convex and concave structures are matching conic, pyramid, or
narrow-to-wide structures.
16. A camera system configured to provide three focal positions,
the camera system comprising: a first focal position prohibiting
cant of lenses within a lens housing relative to a plane of an
image sensor using a mechanical stop and a first mechanical
stop-mate, the mechanical stop configured to mate with the first
mechanical stop-mate effective to prevent non-cant movement of an
image center of a scene on the image sensor and to prevent cant of
the lens housing relative to a planar cross section of at least one
of the lenses, the planar cross section parallel to a plane of the
image sensor; a second focal position prohibiting cant of the
lenses within the lens housing relative to the plane of the image
sensor using the mechanical stop and a second mechanical stop-mate;
and a third focal position between the first and second focal
position, the third focal position enabling focus of a scene on the
image sensor at focal distances less that the first position and
greater than the second position.
17. The camera system as recited in claim 16, further comprising:
springs having a spring force by which the first position or the
second position is provided; and electromagnets having a magnetic
force when provided a current by which another of the first
position or the second position is provided.
18. The camera system as recited in claim 16, wherein the
mechanical stop comprises a ring surrounding the lens housing.
19. The camera system as recited in claim 16, further comprising a
focusing module configured to provide a force by which to provide
the first or second position.
20. The camera system as recited in claim 19, wherein the focusing
module powers an electromagnet effective to balance a spring force
of a mechanical spring or springs at the first or second position,
the balancing providing the third position.
Description
BACKGROUND
Currently, small and thin cameras have a collection of lenses that
are moved to and from an image sensor to focus on a particular
scene. To make this movement of the lenses, many devices rely on
voice-coil motors (VCMs), which use some form of mechanical spring
along with an electromagnet. The spring draws the lenses one
direction and the electromagnet, under control of the device, moves
the lenses an opposite direction. These lens elements are often
placed within a barrel or cylindrical housing, which moves along a
track within another structure. These current structures permit
good imaging for cameras within small or thin devices.
These current devices, however, permit the housing to cant or tilt.
This canting, even at a very small angle, can reduce image quality,
especially for array cameras. Array cameras have multiple image
sensors and lens collections to capture multiple images. Array
cameras then combine these multiple captured images to create a
final resulting image that is of high quality. The quality of this
resulting image, however, can be substantially reduced with even a
very small amount of cant in any one of the lens collections.
The cant is often caused by the springs and the electromagnets not
being in perfect balance, for example, one spring being stronger
than the other or one area of the electromagnet having a stronger
force on it, or caused by it, than another area. When this happens,
two problems arise, a loss of focus on some area of the image
sensor or an image capture that is misaligned. The first problem
affects even a camera with a single image sensor, while both affect
array cameras. Loss in image quality for array cameras can also be
due to the effect on the camera's intrinsic matrix when different
lens collections cant differently, which adversely affects array
camera calibration, causing the eventual fused image to be fused
improperly.
This background description is provided for the purpose of
generally presenting the context of the disclosure. Unless
otherwise indicated herein, material described in this section is
neither expressly nor impliedly admitted to be prior art to the
present disclosure or the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Apparatuses of and techniques enabling non-canting VCM-actuated
autofocus are described with reference to the following drawings.
The same numbers are used throughout the drawings to reference like
features and components:
FIG. 1 illustrates cant of a lens housing.
FIG. 2 illustrates an example environment in which non-canting
VCM-actuated autofocus can be enabled.
FIG. 3 illustrates example image sensors of a camera system of FIG.
2.
FIG. 4 illustrates a two-position camera system having an image
sensor, a lens stack, a lens housing, springs, electromagnets,
mechanical stops, and mechanical stop-mates.
FIGS. 5-7 illustrate convex and concave mechanical stops and
stop-mates.
FIG. 8 illustrates a planar-ring stop-mate having mechanical stop
planes configured to contact mechanical stop-mates, which are also
planar and configured as rings.
FIG. 9 illustrates a camera system having three focal
positions.
FIG. 10 illustrates a camera system having three focal positions
with mechanical stops and stop-mates that reduce movement of an
image center.
FIG. 11 illustrates the computing device of FIG. 2 in greater
detail.
FIG. 12 illustrates example methods for controlling a voice-coil
motor effective to autofocus without canting.
FIG. 13 illustrates various components of an electronic device that
can implement non-canting VCM-actuated autofocus in accordance with
one or more embodiments.
DETAILED DESCRIPTION
Voice-Coil Motors (VCMs) are a common and conventional mechanism to
autofocus a camera, especially those with thin form factors present
in smartphones and tablets. VCMs use a combination of springs and
electromagnetic force to adjust a position of a lens relative to an
image sensor to focus on an object. VCMs suffer from an effect
called dynamic tilt, where the lens is not moved evenly through the
focus range. Instead, small mismatches in components cause the lens
to tilt or "cant" at various positions of a lens relative to an
image sensor. This is shown in exaggerated form in FIG. 1 with a
cant angle 102 of a lens housing 104 of a VCM-actuated camera. Note
that even very small cant angles can negatively affect image
quality, for example 0.1 to 1.0 degree.
As discussed, the VCM uses a combination of springs and
electromagnetic force to position the lens housing. The cant
problem occurs due to imbalance between these components. During
normal operation, the lens (via the lens housing) is positioned
close to an image sensor for moderate to far object distances and
moves away from the image sensor for close distances, e.g., less
than one meter. As the lens housing is moved toward or away from
the image sensor, the lens housing can cant or tilt, thereby
reducing image quality.
In contrast, techniques and apparatuses are described below that
enable non-canting VCM-actuated autofocus. These techniques and
apparatuses enable multiple focal distances that are substantially
free of imaging errors caused by the above-described canting of a
lens housing or, at a minimum, are recurring and thus correctable.
These multiple focal distances are provided by multiple positions
of a lens housing relative to an image sensor. These positions can
be free of cant through use of mechanical stops and corresponding
mechanical stop-mates. By so doing, lower cost, faster focusing,
higher image quality, lower power, or lower settling time can be
achieved. For example, by using a mechanical stop, some positions
require little power, low settling times, and less sophisticated
controllers due to the positions being set mechanically rather than
through use of electromagnets. As noted, higher image quality can
also be attained due to reduction or elimination of tilt, which
results in image center movement and out-of-focus imaging.
As described below, one-, two-, and three-position VCM cameras are
shown, at least one of the positions of which is defined by
mechanical stops. These mechanical stops can be built into the
structure of the VCM, for example on a lens housing, barrel through
which the lens housing moves, or surrounding structures.
These mechanical stops permit sufficient positions to enable
`standard` and `macro` mode imaging, e.g., imaging of objects that
are about 20 centimeters or less and those about 20 centimeters to
infinity. With a third optional position, the range of focal
imaging can be further expanded, for example to 10-50 centimeters,
50 centimeters to 1.5 meters, and 1.5 meters to infinity By so
doing, cant that is normally exhibited by VCMs can be eliminated or
substantially reduced while providing positions necessary to cover
a vast majority of imaging situations.
The following discussion first describes an operating environment,
then example cameras, a detailed description of an example
computing device having a camera, followed by techniques that may
be employed in this environment and device, and ends with an
example electronic device.
Example Environment
FIG. 2 illustrates an example environment 200 in which non-canting
VCM-actuated autofocus can be embodied. Example environment 200
includes a computing device 202 having a camera system 204
capturing images of a scene 206. Camera system 204 includes an
array of three image sensors 208, each of which includes a lens
stack 210.
Camera system 204 may include one, or be an array of, image sensors
208. When an array, image sensors 208 can be of similar or
dissimilar types. Thus, the sensors can have different numbers of
pixels, color-sensing of pixels, sizes of pixels, or sensor
size.
By way of example, consider FIG. 3, which illustrates image sensors
302 of camera system 204. Image sensor 302-1 is monochrome with a
clear color filter. This monochrome aspect improves signal-to-noise
ratio in low-light situations and can enable a high detail for a
given pixel count, or perform better in low-light environments due
to an improved signal-to-noise ratio (SNR). Further, image sensor
302-1 may include a filter permitting infrared radiation to be
sensed, which may not be desired for color-pixel sensors because
infrared radiation inhibits color fidelity, but does permit
bandwidth captured by the imager to be expanded into the Near
Infrared (NIR). This can improve SNR in low-light scenes, in some
cases permitting image capture in near darkness. Image sensors
302-2 and 302-3 have a lower pixel count using larger-pixel color
sensors, which increases sensitivity, thereby enabling brighter
images with more vivid color.
As this one example shows, array cameras enable various
advancements in thin (and non-thin) cameras but, as noted above,
rely on post-processing of the images captured by each of the image
sensors, in this case two low-pixel-count color images with one
high-pixel-count greyscale image, though this is provided as one
non-limiting example for illustration only. Cant of the lens stack
inhibits this post-processing, as image center movement and focus
errors prohibit the highest image quality.
With an example of an array camera explained, consider FIG. 4,
which illustrates a two-position camera system 402 having an image
sensor 404, a lens stack 406, a lens housing 408, springs 410,
electromagnets 412, mechanical stops 414, and mechanical stop-mates
416. This camera system 402 is shown in cross-sectional view, while
mechanical stops 414-1 and 414-2 are shown in both cross section
and plan views. Mechanical stop 414-3 is not shown in cross section
but is shown in plan view.
Image sensor 404 can be any of those described herein, for example
one of those illustrated in FIG. 3. Lens stack 406 includes one or
more lenses used to project light from a scene and, if moved in a
correct position, focus light from the scene on to image sensor
404. Lens housing 408 houses lenses of lens stack 406. The
particular shape of lens housing 408 can be one of many different
shapes and sizes, whether in one or multiple parts. Here a
cylindrical shape is implemented. In more detail, lens housing 408
includes a lens-retention section 418 and here is shown including
mechanical stop-mates 416 as part of a structure integral with lens
housing 408.
As noted in part above, mechanical stops 414 are configured to
contact mechanical stop-mates 416 effective to prevent cant of the
lens housing. This cant can be prevented such that the lenses are
parallel with image sensor 404. In some cases very slight angles
exist but this small angle can be accounted for during calibration
of the camera system as it should remain consistent. In this
illustrated case a planar cross section 420 of lens 422 is parallel
to a plane 424 of image sensor 404 for both positions in which
mechanical stops 414 contact mechanical stop-mates 416.
The mechanical stops (or sets of them) are both effective to
prevent cant of the lens housing, with one at a first position and
the other at a second position, where each of the positions having
different focal distances to image sensor 404.
Springs 410 provide a spring force by which lens housing is pulled
in a direction, which is often in opposition to a magnetic force of
electromagnets 412. Electromagnets 412 provide a magnetic force
when provided a current by a controller (e.g., in a device having
camera system 402). Note that in this case an intermediate position
is shown where neither of the mechanical stops are in contact with
stop-mates. This is one alternative position described in greater
detail below. Here two positions can be provided by the mechanical
stops when lens housing 408 contacts, through stop-mates 416,
mechanical stops 414-1, 414-2, and 414-3 or 414-4 and 414-5 (one or
more other stops may also be included with stops 414-4 and 414-5,
which are not shown). As shown, mechanical stops 414-1, 414-2, and
414-3 include three projections arranged effective to define a stop
plane that is parallel to planar cross section 420 and plane 424 of
image sensor 404.
In some cases, mechanical stops and stop-mates are configured to
mate sufficient to prevent cant as well as prevent non-cant
movement (e.g., side-to-side) of an image center of the scene on
the image sensor. This is illustrated in FIGS. 5, 6, and 7.
FIG. 5 illustrates convex and concave stops and stop-mates. At one
position, camera system 502 includes mechanical stops 504 that are
convex that mate to stop-mates 506 that are concave. At another
position, camera system 502 includes mechanical stops 508 that are
concave that mate to stop-mates 510 that are convex. As shown,
these convex and the concave structures permit axial perpendicular
movement 512 of lens stack 406 and lens housing 408 relative to
plane 424 of image sensor 404 while prohibiting, on full contact,
axial parallel movements 514 relative to plane 424 of image sensor
404.
FIG. 6 illustrates a camera system 602 having convex stop-mates 604
and 606 and concave mechanical stops 608 and 610, though as part of
a different configuration than FIG. 5. An optional middle position
612 and high and low positions 614 and 616, respectively, are shown
in enlarged form for detail. At high position 614 (far focal
position from image sensor 404) convex stop-mates 604 contact
concave mechanical stops 608. At a low position 616 (closest to
image sensor 404), convex stop-mates 606 contact concave mechanical
stops 610. Note that in this example the convex and concave
structures are matching half spheres. When in full contact, both
sets of mates and stops prevent movement parallel to the plane of
image sensor 404, thereby prohibiting movement of an image center
of a captured scene (e.g., scene 206 of FIG. 2).
Camera system 602 includes mechanical stop-mates as part of a
single structure, though each set of mates and stop-mates may be a
singular structure rather than all mates or stop-mates being one
structure. While not shown by this cross section of FIG. 6, the
mates can be a single ring surrounding lens housing 408.
FIG. 7 illustrates a camera system 702 having convex stop-mates 704
and 706 and concave mechanical stops 708 and 710. Like FIG. 6,
middle, high, and low positions can be provided, though the middle
position is optional (none shown, see FIG. 6). Here, at a far focal
position from image sensor 404, convex stop-mates 704 contact
concave mechanical stops 708. At a near focal position from image
sensor 404, convex stop-mates 706 contact concave mechanical stops
710. In this example, the convex and concave structures are
narrow-to-wide and wide-to-narrow forming a point or pyramid. When
in full contact, both sets of mates and stops prevent movement
parallel to the plane of image sensor 404, thereby prohibiting
movement of an image center of a captured scene (e.g., scene 206 of
FIG. 2). Like some other mates and stops described herein, these
can be two stops and mates at opposing sides of lens housing 408,
three or more stops defining a plane, a consistent structure, for
example, a full ring or plane, or three or more different stops and
mates. FIG. 7 illustrates one particular alternative in which two
convex stop-mates and stops may be used for each of the high and
low positions. Here pyramids of convex stop-mates 704 and 706,
along with matching concave mechanical stops 708 and 710, allow
alignment, reduce tilt, and prevent parallel movement. This is
shown with a top-down plan view illustrating two convex stop-mates
704.
FIG. 8 illustrates one such flat, consistent structure, where
camera system 802 includes a planar-ring stop-mate 804 having
mechanical stop planes 806 and 808 that are configured to contact
mechanical stop-mates 810 and 812, respectively, which are also
planar and configured as rings. Note the plan view showing
mechanical stop plane 806 of planar-ring stop-mate 804 as well as
their relationship to lens housing 814.
While these examples illustrate various stops and stop-mates,
others are also envisioned, for example conic points or
wave-cross-section rings and mates. Many of these structure
prohibit cant, movement of an image center, as well as twist of a
lens housing or lenses of a lens stack (twist can have negative
effects in some applications of array cameras).
While each of the above camera systems are capable of more than two
positions, consider two specific examples of camera systems that
have three or more positions. FIG. 9 illustrates camera system 902
having three focal positions. A middle focal position 904 does not
use mechanical stops and is an equilibrium position caused by
springs 906. Middle focal position 904 includes a middle focal
distance 908 from a nearest lens of lenses 910 relative to image
sensor 912.
FIG. 9 also illustrates a near focal position 914. Near focal
position 914 prohibits cant of lenses 910 and a lens housing 916
(shown in larger illustration) relative to a plane 918 of image
sensor 912 using a mechanical stop 920 and a mechanical stop-mate
922. As shown in one of the smaller illustrations, mechanical stop
920 is in contact with mechanical stop-mate 922, with each having
two points shown in cross section.
Far focal position 924 prohibits cant of lenses 910 within lens
housing 916 (shown in larger illustration) relative to plane 918 of
image sensor 912 using a mechanical stop 926 and a mechanical
stop-mate 928. As shown in this smaller illustration, mechanical
stop 926 is in contact with mechanical stop-mate 928, with each
having two points shown in cross section. Note that the various
other forms of mechanical stops and stop-mates may also be used for
camera system 902, for example those shown in FIGS. 5-8. By way of
one example, FIG. 10 illustrates a camera system 1002 that may also
provide three or more focal positions, in this case with mechanical
stops and stop-mates that further aid to reduce movement of an
image center. Note that the three focal distances 1004, 1006, and
1008 in this example camera system are relatively similar. This is
but one way in which some cameras, whether array cameras or
otherwise, may operate.
Having generally described camera systems, mechanical stops, and
mechanical stop-mates, this discussion now turns to FIG. 11, which
illustrates computing device 202 of FIG. 2 in greater detail.
Computing device 202 is illustrated with various non-limiting
example devices: smartphone 202-1, laptop 202-2, television 202-3,
desktop 202-4, tablet 202-5, and video and still camera 202-6.
Computing device 202 includes processor(s) 1104 and
computer-readable media 1106, which includes memory media 1108 and
storage media 1110. Applications and/or an operating system (not
shown) embodied as computer-readable instructions on
computer-readable media 1106 can be executed by processor(s) 1104
to provide some or all of the functionalities described herein.
Computer-readable media 1106 also includes image manager 1112.
Image manager 1112 is configured to combine or process multiple
images of a same scene to provide a high-quality final image. Thus,
image manager 1112 may create a composite image using multiple
images of the same scene, for example images captured by each of
image sensors 302 of FIG. 3. As noted above, computing device 202
includes camera system 204, which in turn includes lens stack 210
and image sensor 404, as well as a focusing module 1114, which is
configured to control voice-coil motor 1116. Focusing module 1114
may be software or hardware or both (e.g., as an above-mentioned
auto-focus system).
Focusing module 1114, as described below, is configured to control
movement of lens stack 210 (generally via lens housing 408) through
control of voice-coil motor 1116. This control is effective to
cause one or more focal position that are free or relatively free
of cant and/or movement of an image center.
In some cases, computing device 202 is in communication with, but
may not necessarily include, camera system 204 or elements thereof.
Captured images are then received by computing device 202 from
camera system 204 via the one or more I/O ports 1118. I/O ports
1118 can include a variety of ports, for example, by way of example
and not limitation, high-definition multimedia (HDMI), digital
video interface (DVI), display port, fiber-optic or light-based,
audio ports (e.g., analog, optical, or digital), USB ports, serial
advanced technology attachment (SATA) ports, peripheral component
interconnect (PCI) express based ports or card slots, serial ports,
parallel ports, or other legacy ports. Computing device 202 may
also include network interface(s) 1120 for communicating data over
wired, wireless, or optical networks. By way of example and not
limitation, network interface 1120 may communicate data over a
local-area-network (LAN), a wireless local-area-network (WLAN), a
personal-area-network (PAN), a wide-area-network (WAN), an
intranet, the Internet, a peer-to-peer network, point-to-point
network, a mesh network, and the like.
Example Methods
The following discussion describes methods by which techniques are
implemented to enable use of non-canting VCM-actuated autofocus.
These methods can be implemented utilizing the previously described
environment and example camera systems, for example those shown in
FIGS. 2-11. Aspects of these example methods are illustrated in
FIG. 12, which are shown as operations performed by one or more
entities. The orders in which operations of these methods are shown
and/or described are not intended to be construed as a limitation,
and any number or combination of the described method operations
can be combined in any order to implement a method, or an alternate
method.
FIG. 12 illustrates example methods 1200 for autofocusing a camera
system. Note that these operations can be repeated or performed
simultaneously for a camera system having multiple image sensors,
lens stacks, and so forth, e.g., those described in FIG. 3.
At 1202, distance data is received for a scene. In some cases this
is determined using parallax of a stereo camera to compute depth
and thus distance to the scene. Distance data can be determined and
received in manners known, for example through radar, infrared,
SONAR, and SODAR, to name but a few. Using FIG. 2 as an example,
data can be received indicating a distance to some object in scene
206, e.g., a person 212.
At 1204, an autofocus focal position is determined based on the
received data distance. Assume, for illustration, that a user
points the camera of her smartphone toward a person on which the
distance data is based. Focusing module 1114 then determines which
focal distance is appropriate to focus that person on the image
sensor or sensors of the camera system. Here we assume a three
position camera system 902 as shown in FIG. 9.
At 1206, a force is applied by which to move a lens or lens stack
to focus the scene on an image sensor. This force can be an
electromagnetic force, for example, using voice-coil motor 1116 to
cause an electromagnetic force to move from a middle focal position
904 to a high focal position 924. Here focusing module 1114
controls voice-coil motor 1116 to move lens stack 910. This force
can balance another force, e.g., a spring force, or can overcome a
force until a mechanical stop is met. In this case, high focal
position 924 is reached when mechanical stop 926 meets mechanical
stop-mate 928, whereby cant is reduced or removed.
The amount of force applied can be previously determined during
calibration of the camera system. In some cases, however, a
feedback is provided when the mechanical stops and stop-mates meet,
e.g., when completion of an electrical circuit or other electrical
effect to indicate that a full contact with the stop and mate (or
stops and mates if multiples).
Optionally, at 1208, an indication can be provided that the scene
is in focus. This is sometimes simply showing the scene on a screen
in focus, or some other indication that scene is in focus. At this
point a user may select to capture an image or images of the scene
or not. If an array camera, the images can be combined in some
fashion to provide a resulting high quality image.
Returning briefly to FIG. 3, three images are capture of scene 206
through image sensors 302-1, 302-2, and 302-3. These are then used
to create a final image. Here image sensor 302-1 captures a
high-resolution, monochromatic image of scene 206. Using the other
images sensors 302-2 and 302-3, two more images, both color, are
captured. These three are then combined to create a high quality
image. As noted in part above, this combination is aided by these
techniques as both cant and movement of an image center are both
reduced or eliminated. Note also that while the above example
includes three image sensors, two, four, or even many image sensors
can be used. Also, with higher numbers of images sensors, the
techniques can further aid in enabling combination of these many
images.
Example Electronic Device
FIG. 13 illustrates various components of an example electronic
device 1300 that can be implemented as a computing device and/or
camera system, as described with reference to any of the previous
FIGS. 2-12. The electronic device may be implemented as any one or
combination of a fixed or mobile device, in any form of a consumer,
computer, portable, user, communication, phone, navigation, gaming,
audio, camera, messaging, media playback, and/or other type of
electronic device, for example computing device 202 described with
reference to FIGS. 2 and 11.
Electronic device 1300 includes communication transceivers 1302
that enable wired and/or wireless communication of device data
1304, for example, received data, transmitted data, or sensor data
as described above. Example communication transceivers include NFC
transceivers, WPAN radios compliant with various IEEE 802.15
(Bluetooth.TM.) standards, WLAN radios compliant with any of the
various IEEE 802.11 (WiFi.TM.) standards, WWAN (3GPP-compliant)
radios for cellular telephony, wireless metropolitan area network
(WMAN) radios compliant with various IEEE 802.16 (WiMAX.TM.)
standards, and wired local area network (LAN) Ethernet
transceivers.
Electronic device 1300 may also include one or more data input
ports 1306 via which any type of data, media content, and/or inputs
can be received, for example, user-selectable inputs, messages,
music, television content, recorded video content, and any other
type of audio, video, and/or image data received from any content
and/or data source (e.g., other image devices or image sensors).
Data input ports 1306 may include USB ports, coaxial cable ports,
and other serial or parallel connectors (including internal
connectors) for flash memory, DVDs, CDs, and the like. These data
input ports may be used to couple the electronic device to
components (e.g., camera system 204), peripherals, or accessories
for example, keyboards, microphones, cameras, and printers.
Electronic device 1300 of this example includes processor system
1308 (e.g., any of application processors, microprocessors,
digital-signal-processors, controllers, and the like), or a
processor and memory system (e.g., implemented in a SoC), which
process (i.e., execute) computer-executable instructions to control
operation of the device. Processor system 1308 may be implemented
as an application processor, embedded controller, microcontroller,
and the like. A processing system may be implemented at least
partially in hardware, which can include components of an
integrated circuit or on-chip system, digital-signal processor
(DSP), application-specific integrated circuit (ASIC),
field-programmable gate array (FPGA), a complex programmable logic
device (CPLD), and other implementations in silicon and/or other
hardware.
Alternatively or in addition, electronic device 1300 can be
implemented with any one or combination of software, hardware,
firmware, or fixed logic circuitry that is implemented in
connection with processing and control circuits, which are
generally identified at 1310 (processing and control 1310).
Hardware-only devices in which non-canting VCM-actuated autofocus
may be embodied include those that convert, without computer
processors, sensor data into voltage signals by which to control
focusing systems (e.g., focusing module 1114).
Although not shown, electronic device 1300 can include a system
bus, crossbar, or data transfer system that couples the various
components within the device. A system bus can include any one or
combination of different bus structures, for example, a memory bus
or memory controller, a peripheral bus, a universal serial bus,
and/or a processor or local bus that utilizes any of a variety of
bus architectures.
Electronic device 1300 also includes one or more memory devices
1312 that enable data storage, examples of which include random
access memory (RAM), non-volatile memory (e.g., read-only memory
(ROM), flash memory, EPROM, EEPROM, etc.), or a disk storage
device. Memory device(s) 1312 provide data storage mechanisms to
store the device data 1304, other types of information and/or data,
and various device applications 1314 (e.g., software applications).
For example, operating system 1316 can be maintained as software
instructions within memory device 1312 and executed by processor
system 1308. In some aspects, image manager 1112 and/or focusing
module 1114 is embodied in memory devices 1312 of electronic device
1300 as executable instructions or code. Although represented as a
software implementation, image manager 1112 and focusing module
1114 may be implemented as any form of a control application,
software application, signal-processing and control module, or
hardware or firmware.
Electronic device 1300 also includes audio and/or video processing
system 1318 that processes audio data and/or passes through the
audio and video data to audio system 1320 and/or to display system
1322 (e.g., a screen of a smart phone or camera). Audio system 1320
and/or display system 1322 may include any devices that process,
display, and/or otherwise render audio, video, display, and/or
image data. Display data and audio signals can be communicated to
an audio component and/or to a display component via an RF (radio
frequency) link, S-video link, HDMI (high-definition multimedia
interface), composite video link, component video link, DVI
(digital video interface), analog audio connection, or other
similar communication link, e.g., media data port 1324. In some
implementations, audio system 1320 and/or display system 1322 are
external components to electronic device 1300. Alternatively or
additionally, display system 1322 can be an integrated component of
the example electronic device, for example, part of an integrated
touch interface. Electronic device 1300 includes, or has access to,
a camera system, which includes lens stack 210 and image sensor 302
or 404 (not shown). Sensor data is received from camera system 204
and/or image sensor 302 or 404 by image manager 1112, here shown
stored in memory devices 1312, which when executed by processor
system 1308 constructs a final image as noted above.
Although embodiments of non-canting VCM-actuated autofocus have
been described in language specific to features and/or methods, the
subject of the appended claims is not necessarily limited to the
specific features or methods described. Rather, the specific
features and methods are disclosed as example implementations of
non-canting VCM-actuated autofocus.
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